docs: def vprjp(vin, plane):
      """
      Project a vector onto a specified plane, orthogonally.
  
      http://naif.jpl.nasa.gov/pub/naif/toolkit_docs/C/cspice/vprjp_c.html
  
      :param vin: The projected vector. 
      :type vin: 3-Element Array of floats
      :param plane: Plane containing vin. 
      :type plane: spiceypy.utils.support_types.Plane
      :return: Vector resulting from projection.
      :rtype: 3-Element Array of floats
      """
      vin = stypes.toDoubleVector(vin)
      vout = stypes.emptyDoubleVector(3)
      libspice.vprjp_c(vin, ctypes.byref(plane), vout)
      return stypes.cVectorToPython(vout)